\[W_{n,4}(u,\xi)=|\xi|^{1/2}Y_{\nu}\left(u|\xi|^{1/2}\right)\sum_{s=0}^{n-1}%
\frac{A_{s}(\xi)}{u^{2s}}-|\xi|Y_{\nu+1}\left(u|\xi|^{1/2}\right)\sum_{s=0}^{n%
-2}\frac{B_{s}(\xi)}{u^{2s+1}}+|\xi|^{1/2}\operatorname{env}\mskip-2.0muY_{\nu%
}\left(u|\xi|^{1/2}\right)O\left(\frac{1}{u^{2n-1}}\right),\]